This application includes subject matter disclosed and claimed in my U.S. application Ser. No. 30,794 filed Apr. 17, 1979 and now issued as U.S. Pat. No. 4,250,799 on Feb. 17, 1981 and entitled "Sweeping Air Stream Apparatus and Method", and my U.S. application Ser. No. 119,699 filed Feb. 8, 1980 and issued as U.S. Pat. No. 4,336,909 on June 29, 1982 entitled "Oscillating Reed and Method".
The subject matter is also related to subject matter disclosed in my divisional application Ser. No. 302,285 filed Sept. 14, 1981 and entitled "Oscillating Reed and Method" and my divisional application Ser. No. 200,611 filed Oct. 24, 1980 entitled "Sweeping Air Stream Apparatus and Method" which is a division of my U.S. Pat. No. 4,250,799.
The invention generally is directed to air flow and distribution systems and in particular, to the treated air flow systems in automobiles such as defrosters, air conditioning and heating systems.
In automobile systems, the defrost system and the air conditioning system as well as the heating system typically are all contained under the dashboard and prior art efforts to use standard (feedback) type fluidic nozzles while, basically, functionally good in sweeping a jet of air across the windshield, physical size of the fluidic element in much too large to fit within the dash, particularly in small and downsized automobiles. For example, the outlet of some automobile ducting is about 3.times.5 inches. If one were to use the samller 3" dimension for the power nozzle width (W) of the fluidic element, the resultant length of the nozzle would be too long. Experiments with the resultant sweeping air jet from such a large element to discover more about its uniformity characteristics in the air showed that the frequency standard of the oscillator is in the order of 10 H.sub.z and at an air velocity of about 100 feet per second the characteristic wavelength is in the order of about 10 feet which is satisfactory. Various electrically powered oscillatory elements have been suggested, however they add cost, complexity and maintenance problems and are not silent.
The operational basis for the oscillating jet is that a concentrated jet would be uniformly swept over the windshield so that the intensity of the heat, because of minimal mixing with ambient, would be maximized at the point of impact of the air stream but would be uniformly distributed by the sweeping action. In order to accomplish this, the sweeping rate or frequency of the air stream must be low enough compared to the velocity of the air jets so that the wavelength is long compared to the nozzle. When the wavelength is long, a small portion of the stream resides in the ambient air before impacting the windshield. On the other hand, with a short wavelength much of the stream resides in the ambient air, producing severe mixing with the ambient, which for defrost purposes tends to defeat the purpose at hand. However, for air conditioning purposes, a low sweeping rate is desired in the initial cool down phase of the air confined within the automobile and, after the vehicle has been cooled down, a mixing with the ambient is desired so as to maintain the temperature. This dual sweep frequency concept is also desirable for the heating of the vehicle that is to say, the initial heating is obtained by a low rate or frequency of sweeping of the air stream in the passenger compartment in order to more rapidly cool down or heat up the passenger compartment and then, after a short time interval the sweep rate is increased to thereby produce mixing of the freshly cooled or heated air with the air in the passenger compartment.
In order to satisfy the requirement of small space and to minimize ambient mixing for defrost operation (which is undesirable since it lowers the thermal energy of air impacting the windshield), the present invention provides an oscillator whose frequency is independent of the air stream properties and whose frequency is characteristically low. However, the invention also provides an oscillator whose frequency can be changed dependent upon time and/or temperature to achieve an initial low frequency of operation so as to assure a rapid heating and/or cooling of the passenger compartment and subsequently, a higher frequency of oscillation to assure a better mixing characteristic (in contrast to the defrost operation) after the passenger compartment has been cooled or heated for a selected period of time.
The present invention provides a vibrating reed air stream oscillator, constituted by a thin resilient vane in the shape of an inverted "T" which is supported in cantilevered fashion from the stem of the "T" in the duct. This provides an air initiated oscillation mechanism which is extremely reliable, very low in cost and can be installed or incorporated in existing defrost systems without significant structural modification and which does not require any additional space. In fact, the invention can reduce the space requirements since it results in a much more efficient and rapid defrost of an automobile windshield by concentrating the heated air rather than diffusing it over a wide or long path. That is to say, instead of a diffuser of wide angles, the air stream is swept over the wide angle and, in some cases, a single defrost air outlet adjacent to the windshield can accommodate the entire windshield.
The oscillating element of the present invention solves the problems in a simple, efficient relatively maintenance free and inexpensive manner.
According to the invention an oscillatory member is supported in the air outlet element of an automobile air flow system, said oscillatory member being constituted by a resilient vane or reed secured at its downstream end proximate the center of the air outlet element, the free upstream end has a weighted, air impingement surface and is proportioned with respect to the cross-sectional size of the outlet element that during oscillatory movement there is no physical contact with any structural portion of the outlet elements. In defrost/defog systems, the frequency of oscillation is such that the wavelength is long relative to the distance from the outlet element to the windshield surface thereby minimizing mixing of defrost/defog air with ambient air. In heating and air conditioning systems higher initial frequencies, and hence shorter wavelength, are desireable to obtain better mixing to obviate hot or cold spots. Rapid heating/cooling of the passenger compartment, initially requires subsequently lower frequency-longer wavelength.
The vane is fairly broad and wide and acts like a moving wall to deflect or direct the exiting air jet stream in a sweeping fashion. Since the reed or vane is wide and its upstream end unsupported and during its travel in any direction it must not contact any structure, the fluid air stream can and do at times distort the bending axis of the reed and thereby creating a clicking. However, such noise making is very undesirable particularly in the closed space of an automobile and, because of the distortion in the spring metal itself, tends to greatly reduce the life of the element when used as an oscillator. A further feature of the present invention provides improved oscillating reed structures which are essentially clickless or noiseless and have long operating lifes.
In a first embodiment this is achieved by providing a transverse stiffening of the reed element in directions transverse to the direction of air flow so as to limit bending of the reed element during its oscillations along an axis which is transverse to the direction of air flow. That is to say, the axis of stiffening is parallel to the bending axis but it does not detract from the flexibility and oscillating function of the device. In a preferred embodiment, the bending is a gentle curvature of bending of the reed element over substantially the entire body. In addition, the body of the reed support element has a slot in it with the mouth of the slot gently rounded or smoothed to receive and clamp the downstream end of the reed element so that there are no sharp edges against which the body of the reed element is engaged during oscillation. Moreover the edges of the reed element is polished to remove notches etc. . . . all of these features avoiding metal fatigue of the reed body leading to extended life of the oscillator element per se.
In a further embodiment, the oscillating vane is constituted by a pair of spaced coil springs with an elastomeric sheet between them and a weight. This flexible assembly is inherently clickless and the stress in the coil spring is very low even for large flexural deflections so that fatigue is no problem. Apart from the requirement that there be no physical contact with sidewalls etc. . . . handling of the materials or precise tolerance is required.